Hepatitis E virus chimeric DNA vaccine elicits immunologic response in mice

AIM： To construct the plasmid pcHEV23 containing fragments of HEV ORF2 and ORF3 chimeric gene and to assess its ability to elicit specific immunologic response in mice. METHODS： The gene encoding the structural protein of HEV ORF2 fragment and full-length ORF3 was amplified by PCR. The PCR products were cloned into an eucaryotic expression plasmid pcDNA3. The resulting plasmid pcHEV23 was used as a DNA vaccine to inoculate BALB/c mice intramuscularly thrice at a dose of 100 or 200 ug. Mice injected with empty pcDNA3 DNA or saline served as control and then specific immune responses in the mice were detected. RESULTS： After 2-3 times of inoculation, all mice injected with pcHEV23 had anti-HEV IgG seroconversion and specific T lymphocyte proliferation. The lymphocyte stimulation index in the group immunized with pcHEV23 （3.1＋0.49） was higher than that in the control group （0.787±0.12, P〈0.01）. None in the control group had a detectable level of anti-HEV IgG. CONCLUSION： DNA vaccine containing HEV ORF2 and ORF3 chimeric gene can successfully induce specific humoral and cellular immune response in mice.

Cloning and expression of cDNAs from hepatitis E virus structural gene

OBJECTIVE: To obtain recombinant antigen for development of anti-HEV ELISA kit and vaccine against hepatitis E virus infection. METHODS: A 492 base cDNA was collected from 5'-terminus of open reading frame 2 (ORF2) among epidemic hepatitis E virus (HEV) isolated from Xinjiang, Western China. The fragment was digested with BamH I and EcoR I, and inserted into vector pGEX-4T-3 which was also digested by the same enzyme. The recombinant plasmid was transformed into E. coli TG-1 and the fusion protein expressed was confirmed by Western blot analysis using serum of a patient with hepatitis E. RESULTS: The recombinant plasmid was identified and confirmed with enzyme digestion, polymerase chain reaction (PCR) and sequencing, respectively. A protein band of about 46 kDa was demonstrated by SDS-PAGE and designated GST-pORF2. The result of Western blot analysis suggested that the fusion protein reacted with anti-HEV positive sera at a dilution of 1:100. CONCLUSION: The recombinant protein GST-pORF2 may be useful in developing anti-HEV ELISA kit and vaccine against hepatitis E virus infection.

A Severe Seasonal Influenza Epidemic During 2017–2018 in China After the 2009 Pandemic Influenza: A Modeling Study

Influenza viruses continue to cause epidemics worldwide every year.However,due to the lack of an effective assessment for the severity of influenza epidemics,it was extremely difficult to take preventative measures.Data were extracted from infectious diseases reports from 2011–2018.Joinpoint regression model and susceptible-exposed-infectious-recovered model were built to understand the characteristics and processes of the epidemic.The reported incidence of influenza was 1,913,698 from January 2011 to February 2018,with an average-yearly-reported-incidence-rate of 19.21 per 100,000.However,there had been a substantial nationwide epidemic of influenza after September 2017,when the average yearly reported incidence rate was 87.29 per 100,000 and an annual percentage change of 48.1%.The hemagglutinin genes of most influenza A(H1N1 and H3N2)viruses from the period of the epidemic had lower homology to those before August 2017.All the hemagglutinin of the recommended A(H3N2,H1N1)and B(Victoria)viruses for vaccines 2017/2018 had low matches with the epidemic viruses.The basic reproduction number was 1.53.The vaccination benefit was linearly related to vaccination coverage,while the quarantine measure had only significantly benefited when over 60%of the quarantined population.The most severe epidemic of influenza in China since 2011 occurred during the period from September 2017 to February 2018.Compared to quarantine,influenza vaccination is more effective way to prevent influenza,and strategies to increase vaccination coverage should be taken for the prevention of severe epidemics of influenza.